"Definite evidence" in these situations is not an absolute term. eg. When Kasab was caught red-handed in Mumbai attacks, Pakistan initially refused to agree that he was theirs.
– Bruce LeeJun 3 '18 at 20:45

1 Answer
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On the other issue, as a former head of the US Central Command Mattis
appreciates Pakistan’s indispensability as base for military
operations to bring the Taliban in Afghanistan to their knees. But
Islamabad has insisted that India’s role in Afghanistan be restricted
and complained about the Indian support for the Tehrik-e-Taliban
Pakistan (TTP) accused by Islamabad of terrorism in Pakistan. The
RAW-TTP link was publicly revealed in April this year by its former
commander, Ehsanullah Ehsan.

Mattis’ request that India moderate its support for TTP will put Delhi
in a fix because TTP is useful as an Indian counterpart of the Hizbul
Mujahideen, Lashkar-e-Toiba, and Jaish-e-Mohammad deployed by the
Pakistan Inter-Services Intelligence (ISI) in Jammu & Kashmir.
Severing relations with TTP will mean India surrendering an active
card in Pakistan and a role in Afghanistan as TTP additionally
provides access to certain Afghan Taliban factions.

This means Indian government has a definite collaboration with some terrorists in Pakistan notably TTP.